Preterm Birth, Social Disadvantage, and Cognitive Competence in Swedish 18- to 19-Year-Old Men

Department of Women and Children Health, Sachs Children's Hospital, Karolinska Institutet, Stockholm, Sweden.
PEDIATRICS (Impact Factor: 5.47). 12/2009; 125(1):e67-73. DOI: 10.1542/peds.2008-3329
Source: PubMed


The aim was to study the impact of a range of gestational ages (GAs) on cognitive competence in late adolescence and how this effect is modified by contextual social adversity in childhood.
This was a register study based on a national cohort of 119664 men born in Sweden from 1973 to 1976. Data on GA and other perinatal factors were obtained from the Medical Birth Register, and information on cognitive test scores was extracted from military conscription at the ages of 18 to 19 years. Test scores were analyzed as z scores on a 9-point stanine scale, whereby each unit is equivalent to 0.5 SD. Socioeconomic indicators of the childhood household were obtained from the Population and Housing Census of 1990. The data were analyzed by multivariate linear regression.
The mean cognitive test scores decreased in a stepwise manner with GA. In unadjusted analysis, the test scores were 0.63 stanine unit lower in men who were born after 24 to 32 gestational weeks than in those who were born at term. The difference in global scores between the lowest and highest category of socioeconomic status was 1.57. Adjusting the analysis for the childhood socioeconomic indicators decreased the effect of GA on cognitive test scores by 26% to 33%. There was also a multiplicative interaction effect of social adversity and moderately preterm birth on cognitive test scores.
This study confirms previous claims of an incremental association of cognitive competence with GA. Socioeconomic indicators in childhood modified this effect at all levels of preterm birth.

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    • "Exposure to socioeconomic disadvantage during pregnancy and early childhood impairs neurodevelopment in children [1,2]. Despite evidence indicating that the association between socioeconomic position (SEP) and the neurodevelopment of newborns and young children [3-9], the results of epidemiological studies on the association of SEP with later neurodevelopment have been inconsistent [6,7,10]. "
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    ABSTRACT: Caste, a proxy of socioeconomic position, can influence the neurodevelopment of children through several pathways, including exposure to toxic elements. Studies from developing countries where caste is represented by prevailing caste groups and people are highly exposed to toxic elements can provide useful insights into the mechanisms of neurodevelopmental inequities among children. This study aims to investigate the impact of caste on the neurodevelopment of children from birth to 36 months of age in Chitwan Valley, Nepal, where people are exposed to high levels of arsenic (As) and lead (Pb). Participants (N = 94) were mother-infant pairs from the Chitwan district in Nepal. The neurodevelopment of the infants was assessed using the Brazelton Neonatal Behavioral Assessment Scale, Third Edition, (NBAS III) at birth and the Bayley Scales of Infant Development, Second Edition, (BSID II) at ages 6, 24, and 36 months. Caste was categorized based on surname, which, in Nepal generally refers to one of four caste groups. We also measured the concentrations of As and Pb in cord blood. Caste was positively associated with the state regulation cluster score of the NBAS III at birth after adjustment for covariates (p for trend < 0.01). Adding cord blood As levels attenuated the association (p for trend = 0.12). With regard to neurodevelopment at six months of age, the third-ranked caste group scored higher than the first-ranked caste group on the Mental Development Index (MDI) of the BSID II (coefficient = 3.7; 95% confidence interval (CI) = 1.3 to 6.0). This difference remained significant after adjustment for cord blood As levels and other covariates was made (coefficient = 3.9; 95% CI = 1.2 to 6.7). The remaining clusters of the NBAS III and BSID II at 6, 24, and 36 months were not significantly associated with caste group. Caste was positively associated with the state regulation cluster score of NBAS III at birth. This association was partially mediated by cord blood As levels. However, the negative impact of caste on neurodevelopment disappeared as the children grew. Furthermore, an inverse association between caste and MDI at six months of age was observed. Additional studies are needed to elucidate the mechanism of how caste affects neurodevelopment.
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    • "It is the leading cause of death in the first month of life and preterm neonates are at an increased risk for post-neonatal mortality and a wide range of respiratory, infectious, metabolic and nervous system morbidities [2,3]. These risks persist beyond the neonatal period – preterm birth is the second leading cause of death in children under 5 [4] and preterm infants have more illnesses, hospital admissions and educational and behavioral problems in childhood and early adulthood [5-8]. They are also at greater risk of adult chronic diseases, such as hypertension and diabetes [9]. "
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    • "In addition, they were followed by post hoc analyses using a groupbased approach involving birth status as a categorical indicator of prematurity. Following common clinical classification systems and discontinuous findings for the cognitive domain (Ekeus et al., 2010; Engle, 2006; Goldenberg et al., 2008; MacKay et al., 2010), these post hoc analyses compared very preterm children (GA < 32 weeks and/or BW < 1500 g, n = 58) vs. moderately to late preterm children (GA ≥ 32 weeks and BW ≥ 1500 g, n = 88). Performance of both preterm groups was contrasted to that of the full-term group. "
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    ABSTRACT: High negative reactivity in early childhood interferes with later academic and behavioral adjustment. Thus, investigating the origins of high negative affectivity in early childhood is of high relevance for understanding emotional morbidity after preterm birth. The present work explored (1) direct prematurity-related consequences for negative reactivity, (2) self-regulatory deficits as a mechanism indirectly relating prematurity to negative affectivity and (3) the implications of the interplay between procedural distress in the neonatal period and parenting stress for preterm children's negative reactivity. The sample was comprised of 146 preterm children (very vs. moderately to late preterm) and 86 healthy full-term children, both free of major neurological impairment. Assessment involved negative affect and parenting stress (parent-report; 12, 24 months corrected age, CA), effortful control (behavioral battery, parent report; 24 months CA) and the number of potentially distressing neonatal intensive care procedures as well as severity of illness during the neonatal period (retrospective chart review). There was no direct link from prematurity to a disposition for high negative reactivity in early childhood nor was prematurity indirectly associated with higher negative reactivity through lower levels of effortful control. The relation between neonatal pain and distress and negative affectivity depended on the level of parenting stress with low parenting stress at the end of the first year of children's life buffering the negative influence of neonatal distress. The present findings underscore the importance of complex interactions among environmental factors in processes of emotional plasticity after preterm birth thereby providing critical suggestions for follow-up care.
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